JP2020125039A - Working vehicle - Google Patents

Working vehicle Download PDF

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Publication number
JP2020125039A
JP2020125039A JP2019018982A JP2019018982A JP2020125039A JP 2020125039 A JP2020125039 A JP 2020125039A JP 2019018982 A JP2019018982 A JP 2019018982A JP 2019018982 A JP2019018982 A JP 2019018982A JP 2020125039 A JP2020125039 A JP 2020125039A
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Prior art keywords
oil
operation valve
power steering
steering device
hydraulic pump
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JP2019018982A
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Japanese (ja)
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JP7106466B2 (en
Inventor
中地　克
Katsu Nakachi
克 中地
威史 土屋
Takeshi Tsuchiya
威史 土屋
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Kubota Corp
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Kubota Corp
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Priority to JP2019018982A priority Critical patent/JP7106466B2/en
Priority to US16/693,773 priority patent/US11161543B2/en
Priority to EP19212318.0A priority patent/EP3693215B1/en
Publication of JP2020125039A publication Critical patent/JP2020125039A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62D—MOTOR VEHICLES; TRAILERS
    • B62D5/00—Power-assisted or power-driven steering
    • B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
    • B62D5/07—Supply of pressurised fluid for steering also supplying other consumers ; control thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60P—VEHICLES ADAPTED FOR LOAD TRANSPORTATION OR TO TRANSPORT, TO CARRY, OR TO COMPRISE SPECIAL LOADS OR OBJECTS
    • B60P1/00—Vehicles predominantly for transporting loads and modified to facilitate loading, consolidating the load, or unloading
    • B60P1/04—Vehicles predominantly for transporting loads and modified to facilitate loading, consolidating the load, or unloading with a tipping movement of load-transporting element
    • B60P1/16—Vehicles predominantly for transporting loads and modified to facilitate loading, consolidating the load, or unloading with a tipping movement of load-transporting element actuated by fluid-operated mechanisms
    • B60P1/162—Vehicles predominantly for transporting loads and modified to facilitate loading, consolidating the load, or unloading with a tipping movement of load-transporting element actuated by fluid-operated mechanisms the hydraulic system itself
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
    • F15B1/02—Installations or systems with accumulators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B7/00—Systems in which the movement produced is definitely related to the output of a volumetric pump; Telemotors
    • F15B7/001—With multiple inputs, e.g. for dual control

Abstract

To prevent a load-carrying platform from being lifted even if a surge pressure is generated in a power steering device in a working vehicle which includes the power steering device and a dump cylinder for performing a swinging and lifting operation of the load-carrying platform and uses a hydraulic pump for supplying pressure oil to the dump cylinder also as a hydraulic pump for supplying pressure oil to the power steering device.SOLUTION: In a working vehicle, an operation valve 20 of a dump cylinder 9 includes a bypass flow passage 35 which supplies pressure oil from a hydraulic pump 14 to a power steering device 10 in a neutral state of the operation valve 20. An oil supply passage 36 with an orifice is provided to supply a hydraulic pressure from the hydraulic pump 14 to a rod side oil chamber 9a of the dump cylinder 9 in the neutral state of the operation valve 20.SELECTED DRAWING: Figure 2

Description

本発明は、走行車輪を操向操作する油圧式のパワーステアリング装置と、上下揺動可能な荷台と、前記荷台に連動連結され、伸長作動によって前記荷台を上昇揺動操作し、短縮作動によって前記荷台を下降揺動操作する油圧式かつ複動形のダンプシリンダと、が備えられた作業車に関する。 The present invention relates to a hydraulic power steering device for steering and manipulating traveling wheels, a vertically swingable loading platform, and an interlocking connection with the loading platform, and an ascending/descending operation of the loading platform by an extension operation and a shortening operation. The present invention relates to a work vehicle including a hydraulic and double-acting dump cylinder that lowers and swings a platform.

上記した作業車において、ダンプシリンダの操作弁に圧油を供給する油圧ポンプと、操作弁に形成され、操作弁の中立状態で油圧ポンプからの圧油をパワーステアリング装置に供給するバイパス流路と、が備えられたものがある。これは、操作弁が中立状態にあると、油圧ポンプによってパワーステアリング装置に圧油が供給されて、パワーステアリング装置による走行車輪の操向操作が可能なり、ダンプシリンダに圧油を供給する油圧ポンプをパワーステアリング装置に圧油を供給する油圧ポンプに兼用するものである。この種のものとして、例えば特許文献１に示されるダンプ式運搬車がある。このダンプ式運搬車には、ダンプシリンダとしての油圧シリンダ、操作弁としての三位置切換弁、三位置切換弁に圧油を供給する油圧ポンプ、油圧式パワーステアリング装置、バイパス流路としてのセンターバイパス流路が備えられている。 In the above-mentioned work vehicle, a hydraulic pump that supplies pressure oil to the operation valve of the dump cylinder, and a bypass flow path that is formed in the operation valve and that supplies pressure oil from the hydraulic pump to the power steering device in a neutral state of the operation valve. Some are equipped with. This is because the hydraulic pump supplies pressure oil to the power steering device when the operation valve is in a neutral state, and the steering wheel can be operated by the power steering device to supply pressure oil to the dump cylinder. Is also used as a hydraulic pump for supplying pressure oil to the power steering device. As this type, for example, there is a dump truck shown in Patent Document 1. This dump truck includes a hydraulic cylinder as a dump cylinder, a three-position switching valve as an operating valve, a hydraulic pump that supplies pressure oil to the three-position switching valve, a hydraulic power steering device, and a center bypass as a bypass flow path. A flow path is provided.

特開昭５８−９３６３３号公報JP-A-58-93333

従来の場合、パワーステアリング装置のストロークエンドまでの操作が頻繁に行われるなど、パワーステアリング装置にサージ圧が発生したとき、操作弁が中立状態にあっても、操作弁に掛かるサージ圧のために操作弁の内部で圧油がリークしてリークした圧油がダンプシリンダに掛かる。ダンプシリンダのボトム側油室およびロッド側油室の両方にほぼ同じ強さの圧油が掛かるが、ボトム側油室で圧油を受けるピストンの面積がロッド側油室で圧油を受けるピストンの面積よりも広いので、ボトム側油室でピストンがリーク圧油によって受けるスライド操作力がロッド側油室でピストンがリーク圧油によって受けるスライド操作力よりも強くてダンプシリンダが伸長作動し、荷台が徐々に上昇する。すなわち、パワーステアリング装置の操作によっては、サージ圧が発生して荷台が上昇することがある。 In the conventional case, when surge pressure is generated in the power steering device such as frequent operation until the stroke end of the power steering device, even if the operation valve is in the neutral state, the surge pressure applied to the operation valve is The pressure oil leaks inside the operation valve, and the leaked pressure oil is applied to the dump cylinder. Although pressure oil of approximately the same strength is applied to both the bottom side oil chamber and rod side oil chamber of the dump cylinder, the area of the piston that receives pressure oil in the bottom side oil chamber is the same as that of the piston that receives pressure oil in the rod side oil chamber. Since it is wider than the area, the sliding operation force that the piston receives by the leak pressure oil in the bottom side oil chamber is stronger than the sliding operation force that the piston receives by the leak pressure oil in the rod side oil chamber, and the dump cylinder extends and the loading platform Gradually rises. That is, depending on the operation of the power steering device, surge pressure may occur and the platform may rise.

本発明は、パワーステアリング装置の操作如何にかかわらず荷台が上昇しない作業車を提供する。 The present invention provides a work vehicle in which the platform is not raised regardless of the operation of the power steering device.

本発明による作業車は、
走行車輪を操向操作する油圧式のパワーステアリング装置と、上下揺動可能な荷台と、前記荷台に連動連結され、伸長作動によって前記荷台を上昇揺動操作し、短縮作動によって前記荷台を下降揺動操作する油圧式かつ複動形のダンプシリンダと、前記ダンプシリンダの操作弁に圧油を供給する油圧ポンプと、前記操作弁に形成され、前記操作弁の中立状態で前記油圧ポンプからの圧油を前記パワーステアリング装置に供給するバイパス流路と、前記操作弁の中立状態において、前記油圧ポンプからの圧油を前記ダンプシリンダのロッド側油室に供給するオリフィス付き給油路と、が備えられている。 The work vehicle according to the present invention is
A hydraulic power steering device that steers the traveling wheels, a vertically swingable loading platform, and an interlocking connection with the loading platform. The loading platform is moved up and down by an extension operation, and the loading platform is rocked by a shortening operation. A hydraulic and double-acting dump cylinder that is operated dynamically, a hydraulic pump that supplies pressure oil to the operation valve of the dump cylinder, and a pressure pump from the hydraulic pump that is formed in the operation valve and is in a neutral state of the operation valve. A bypass flow passage for supplying oil to the power steering device, and an oil supply passage with an orifice for supplying pressure oil from the hydraulic pump to a rod side oil chamber of the dump cylinder in a neutral state of the operation valve are provided. ing.

本構成によると、操作弁が中立状態にあると、油圧ポンプからの油圧がオリフィス付き給油路によって減圧されてダンプシリンダのロッド側油室に供給される。これにより、パワーステアリング装置にサージ圧が発生して中立状態にある操作弁の内部でリークした油圧がダンプシリンダのボトム側油室及びロッド側油室に掛かっても、ボトム側油室でリーク油圧によってピストンが受けるスライド操作力の強さと、ロッド側油室でリーク油圧によってピストンが受けるスライド操作力の強さとの差がロッド側油室でオリフィス付き給油路からの圧油によってピストンが受けるスライド操作力によってキャンセルされ、パワーステアリング装置に発生したサージ圧による操作弁での油圧のリークにかかわらず、ダンプシリンダが伸長作動しないようにできる。 According to this configuration, when the operation valve is in the neutral state, the hydraulic pressure from the hydraulic pump is reduced by the oil supply passage with the orifice and is supplied to the rod side oil chamber of the dump cylinder. As a result, even if the hydraulic pressure leaked inside the operation valve in the neutral state due to surge pressure generated in the power steering device is applied to the bottom side oil chamber and the rod side oil chamber of the dump cylinder, the leakage hydraulic pressure in the bottom side oil chamber The difference between the strength of the slide operation force that the piston receives by the piston and the strength of the slide operation force that the piston receives by the leak hydraulic pressure in the rod side oil chamber is the slide operation that the piston receives by the pressure oil from the oil supply passage with the orifice in the rod side oil chamber. It is possible to prevent the dump cylinder from extending, regardless of the hydraulic pressure leak in the operating valve due to the surge pressure generated in the power steering device, which is canceled by the force.

操作弁が中立状態にあると、パワーステアリング装置にサージ圧が発生しないときでも、オリフィス付き給油路によってダンプシリンダのロッド側油室に圧油が供給されるが、操作弁とボトム側油室とを接続する操作油路が操作弁でブロックされていてボトム側油室の排油が不能となるので、オリフィス付き給油路によってダンプシリンダのロッド側油室に供給される圧油によるダンプシリンダの作動が発生しない。すなわち、荷台の動きが発生しない。 When the operation valve is in the neutral state, pressure oil is supplied to the rod side oil chamber of the dump cylinder by the oil supply passage with the orifice even when surge pressure does not occur in the power steering device. Since the operation oil passage that connects the oil is blocked by the operation valve and the bottom side oil chamber cannot be drained, the dump cylinder is operated by the pressure oil supplied to the rod side oil chamber of the dump cylinder by the oil passage with the orifice. Does not occur. That is, the movement of the loading platform does not occur.

従って、サージ圧が発生する状態、発生しない状態のいずれでパワーステアリング装置が操作されても荷台が動かない。 Therefore, even if the power steering device is operated either in the state where the surge pressure is generated or in the state where the surge pressure is not generated, the cargo bed does not move.

本発明においては、前記オリフィス付き給油路は、前記操作弁の中立状態で前記バイパス流路と、前記操作弁のシリンダポートと、を接続する状態で前記操作弁に形成されていると好適である。 In the present invention, it is preferable that the oil supply passage with the orifice is formed in the operation valve in a state where the bypass passage and the cylinder port of the operation valve are connected in a neutral state of the operation valve. ..

本構成によると、オリフィス付き給油路を操作弁に形成した簡素な構造で油圧回路を構成しつつ、パワーステアリング装置におけるサージ圧にかかわらず荷台が上昇しない作業車を得られる。 According to this configuration, it is possible to obtain a working vehicle in which the hydraulic circuit is configured with a simple structure in which the oil supply passage with the orifice is formed in the operation valve, and the loading platform does not rise regardless of surge pressure in the power steering device.

多目的作業車の全体を示す左側面図である。It is a left side view showing the whole multi-purpose work vehicle. ダンプシリンダ及びパワーステアリング装置の駆動装置を構成する油圧回路図である。It is a hydraulic circuit diagram which constitutes a drive device of a dump cylinder and a power steering device. 操作弁ユニットの油圧回路図である。It is a hydraulic circuit diagram of an operation valve unit. サイドロプス部材と前連結ロプス部材との連結構造を示す斜視図である。It is a perspective view which shows the connection structure of a side lops member and a front connection lops member.

以下、本発明の一例である実施形態を図面に基づいて説明する。
なお、以下の説明では、多目的作業車の走行車体に関し、図１に示される矢印Ｆの方向を「車体前方」、矢印Ｂの方向を「車体後方」、矢印Ｕの方向を「車体上方」、矢印Ｄの方向を「車体下方」、紙面表側の方向を「車体左方」、紙面裏側の方向を「車体右方」とする。 Hereinafter, an embodiment which is an example of the present invention will be described with reference to the drawings.
In the following description, regarding the traveling vehicle body of the multipurpose work vehicle, the direction of arrow F shown in FIG. 1 is “front of the vehicle body”, the direction of arrow B is “backward of the vehicle body”, the direction of arrow U is “upper vehicle body”, The direction of arrow D is "lower side of the vehicle body", the direction on the front side of the paper surface is "left side of the vehicle body", and the direction on the back side of the paper surface is "right side of the vehicle body".

〔多目的作業車の全体の構成〕
図１に示されるように、多目的作業車は、左右一対の前車輪１が操向可能にかつ駆動可能に装備され、左右一対の後車輪２が駆動可能に装備された走行車体を備えている。走行車体の前部に、運転座席３、前車輪１を操向操作するステアリングホィール４を有する運転部５が形成されている。運転部５に、搭乗空間を覆うロプス６が備えられている。ステアリングホィール４による前車輪１の操向操作は、ステアリングホィール４及び前車輪１に連係されたパワーステアリング装置１０がステアリングホィール４の回転に対応させて前車輪１を操向操作することによって行われる。走行車体の後部に荷台７が設けられている。荷台７の後部と、走行車体の車体フレーム８とが走行車体の横幅方向に延びる連結軸芯Ｐを有する連結機構（図示せず）を介して連結されている。荷台７は、連結軸芯Ｐを揺動支点にして前側部分が上下揺動する状態で車体フレーム８に支持されている。荷台７は、前側部分が下降して車体フレーム８によって下方から受け止め支持される下降姿勢と、前側部分が上昇して車体フレーム８に対して上方に離間した上昇姿勢とにわって揺動昇降可能になっている。荷台７の下部にダンプシリンダ９が連動連結されている。ダンプシリンダ９は、伸長作動によって荷台７を上昇操作し、短縮作動によって荷台７を下降操作する状態で荷台７に連動連結されている。荷台７の下方に、エンジン１６を有する原動部１７が形成されている。 [Overall structure of multipurpose work vehicle]
As shown in FIG. 1, a multipurpose work vehicle includes a traveling vehicle body in which a pair of left and right front wheels 1 are steerably and drivably equipped, and a pair of left and right rear wheels 2 are drivably equipped. .. A driver's seat 3 and a driver's part 5 having a steering wheel 4 for steering the front wheels 1 are formed at the front of the vehicle body. The driving unit 5 is provided with a lops 6 that covers the boarding space. The steering operation of the front wheel 1 by the steering wheel 4 is performed by the steering wheel 4 and the power steering device 10 linked to the front wheel 1 operating the front wheel 1 in response to the rotation of the steering wheel 4. .. A luggage carrier 7 is provided at the rear of the traveling vehicle body. The rear part of the luggage carrier 7 and the vehicle body frame 8 of the traveling vehicle body are coupled to each other via a coupling mechanism (not shown) having a coupling axis P extending in the lateral width direction of the traveling vehicle body. The loading platform 7 is supported by the vehicle body frame 8 in a state in which the front portion swings up and down with the connecting axis P as a swing fulcrum. The loading platform 7 can be swung up and down in a descending posture in which a front portion is lowered and is received and supported by the vehicle body frame 8 from below, and in a rising posture in which the front portion is raised and is separated upward from the vehicle body frame 8. It has become. A dump cylinder 9 is interlockingly connected to the lower portion of the loading platform 7. The dump cylinder 9 is interlockingly connected to the bed 7 in a state in which the bed 7 is lifted by the extension operation and lowered by the shortening operation. A prime mover 17 having an engine 16 is formed below the luggage carrier 7.

〔ダンプシリンダ及びパワーステアリング装置の駆動装置の構成について〕
ダンプシリンダ９は、図２に示されるように、油圧式かつ複動形の油圧シリンダによって構成されている。パワーステアリング装置１０は、図２に示されるように、パワーシリンダ１１、コントロールバルブ１２及びメータリングポンプ１３を有している。パワーステアリング装置１０は、全油圧式のパワーステアリング装置によって構成されている。 [Dump cylinder and power steering device drive device configuration]
As shown in FIG. 2, the dump cylinder 9 is composed of a hydraulic double-acting hydraulic cylinder. As shown in FIG. 2, the power steering device 10 has a power cylinder 11, a control valve 12, and a metering pump 13. The power steering device 10 is composed of an all-hydraulic power steering device.

図２，３に示されるように、ダンプシリンダ９の操作弁２０は、操作弁ユニット２１に備えられている。操作弁２０のポンプポート２２と油圧ポンプ１４の吐出部とが給油路２３によって接続され、油圧ポンプ１４によって操作弁２０のポンプポート２２に圧油が供給されるようになっている。給油路２３は、操作弁ユニット２１の内部に形成された給油路部２３ａと、操作弁ユニット２１の外部に形成された給油路部２３ｂとを有している。操作弁２０のタンクポート２４とタンク２５とが排油路２６によって接続され、操作弁２０からタンク２５への圧油の排出が可能になっている。排油路２６は、操作弁ユニット２１の内部に形成された排油路部２６ａと、操作弁ユニット２１の外部に形成された排油路部２６ｂとを有している。 As shown in FIGS. 2 and 3, the operation valve 20 of the dump cylinder 9 is provided in the operation valve unit 21. The pump port 22 of the operation valve 20 and the discharge portion of the hydraulic pump 14 are connected by an oil supply passage 23, and the hydraulic pump 14 supplies pressure oil to the pump port 22 of the operation valve 20. The oil supply passage 23 has an oil supply passage portion 23 a formed inside the operation valve unit 21 and an oil supply passage portion 23 b formed outside the operation valve unit 21. The tank port 24 of the operation valve 20 and the tank 25 are connected by the oil discharge path 26, and the pressure oil can be discharged from the operation valve 20 to the tank 25. The oil drain passage 26 has an oil drain passage portion 26a formed inside the operation valve unit 21 and an oil drain passage portion 26b formed outside the operation valve unit 21.

図２，３に示されるように、操作弁２０の第１シリンダポート２７とダンプシリンダ９のロッド側油室９ａとが第１操作油路２８によって接続され、操作弁２０からロッド側油室９ａへの圧油の供給と、ロッド側油室９ａから操作弁２０への圧油の排出とが可能になっている。第１操作油路２８は、操作弁ユニット２１の内部に形成された操作油路部２８ａと、操作弁ユニット２１の外部に形成された操作油路部２８ｂとを有している。操作弁２０の第２シリンダポート２９とダンプシリンダ９のボトム側油室９ｂとが第２操作油路３０によって接続され、操作弁２０からボトム側油室９ｂへの圧油の供給と、ボトム側油室９ｂから操作弁２０への圧油の排出とが可能になっている。第２操作油路３０は、操作弁ユニット２１の内部に形成された操作油路部３０ａと、操作弁ユニット２１の外部に形成された操作油路部３０ｂとを有している。 As shown in FIGS. 2 and 3, the first cylinder port 27 of the operation valve 20 and the rod side oil chamber 9a of the dump cylinder 9 are connected by the first operation oil passage 28, and the operation valve 20 is connected to the rod side oil chamber 9a. It is possible to supply pressure oil to the operation valve 20 from the rod-side oil chamber 9a. The first operation oil passage 28 has an operation oil passage portion 28 a formed inside the operation valve unit 21 and an operation oil passage portion 28 b formed outside the operation valve unit 21. The second cylinder port 29 of the operation valve 20 and the bottom side oil chamber 9b of the dump cylinder 9 are connected by the second operation oil passage 30, and supply of pressure oil from the operation valve 20 to the bottom side oil chamber 9b and the bottom side. The pressure oil can be discharged from the oil chamber 9b to the operation valve 20. The second operation oil passage 30 has an operation oil passage portion 30 a formed inside the operation valve unit 21 and an operation oil passage portion 30 b formed outside the operation valve unit 21.

図２，３に示されるように、操作弁２０の第１バイパスポート３１と、給油路２３から分岐した分岐給油路２３ｃとが接続され、油圧ポンプ１４によって第１バイパスポート３１に圧油が供給されるようになっている。操作弁２０の第２バイパスポート３２とパワーステアリング装置１０の入力ポート３３とがパワステ用給油路３４によって接続され、第２バイパスポート３２からパワーステアリング装置１０に圧油を供給できるようになっている。油圧ポンプ１４によってパワーステアリング装置１０に圧油を供給できるようになっている。パワステ用給油路３４は、操作弁ユニット２１の内部に形成された給油路部３４ａと、操作弁ユニット２１の外部に形成された給油路部３４ｂとを有している。 As shown in FIGS. 2 and 3, the first bypass port 31 of the operation valve 20 and the branched oil supply passage 23 c branched from the oil supply passage 23 are connected, and the hydraulic pump 14 supplies the pressure oil to the first bypass port 31. It is supposed to be done. The second bypass port 32 of the operation valve 20 and the input port 33 of the power steering device 10 are connected by the power steering oil supply passage 34 so that pressure oil can be supplied from the second bypass port 32 to the power steering device 10. .. The hydraulic pump 14 can supply pressure oil to the power steering device 10. The power steering oil supply passage 34 has an oil supply passage portion 34 a formed inside the operation valve unit 21 and an oil supply passage portion 34 b formed outside the operation valve unit 21.

操作弁２０は、図３に示されるように、中立状態Ｎ、上昇操作状態Ｘ、下降操作状態Ｙ及びフローティング状態Ｚの４種の操作状態に切り換え可能に構成されている。図２，３に示されるように、操作弁２０が中立状態Ｎに切り換えられた状態において、第１バイパスポート３１と第２バイパスポート３２とを接続するバイパス流路３５が操作弁２０に形成されている。操作弁２０が中立状態Ｎに切り換えられた状態において、バイパス流路３５と第１シリンダポート２７とを接続するオリフィス付き給油路３６が操作弁２０に形成されている。 As shown in FIG. 3, the operation valve 20 is configured to be switchable to four operation states including a neutral state N, a rising operation state X, a descending operation state Y, and a floating state Z. As shown in FIGS. 2 and 3, a bypass flow passage 35 that connects the first bypass port 31 and the second bypass port 32 is formed in the operation valve 20 when the operation valve 20 is switched to the neutral state N. ing. In the state where the operation valve 20 is switched to the neutral state N, an oil supply passage 36 with an orifice that connects the bypass passage 35 and the first cylinder port 27 is formed in the operation valve 20.

操作弁２０を上昇操作状態Ｘに切り換えることにより、ポンプポート２２が第２シリンダポート２９に接続され、油圧ポンプ１４によってポンプポート２２に供給された圧油が操作弁２０によって第２操作油路３０に供給されて第２操作油路３０からボトム側油室９ｂに供給される。これと共に、第１シリンダポート２７がタンクポート２４に接続され、ロッド側油室９ａの圧油が第１操作油路２８に排出されて第１操作油路２８から操作弁２０及び排油路２６を介してタンク２５に排出される。これにより、ダンプシリンダ９が油圧ポンプ１４からの圧油によって伸長側に駆動される。すなわち、荷台７が上昇操作される。 By switching the operation valve 20 to the raising operation state X, the pump port 22 is connected to the second cylinder port 29, and the pressure oil supplied to the pump port 22 by the hydraulic pump 14 is changed by the operation valve 20 to the second operation oil passage 30. Is supplied to the bottom side oil chamber 9b from the second operation oil passage 30. At the same time, the first cylinder port 27 is connected to the tank port 24, the pressure oil in the rod-side oil chamber 9a is discharged to the first operation oil passage 28, and the operation valve 20 and the oil discharge passage 26 are discharged from the first operation oil passage 28. It is discharged to the tank 25 via. As a result, the dump cylinder 9 is driven to the extension side by the pressure oil from the hydraulic pump 14. That is, the loading platform 7 is lifted.

操作弁２０を下降操作状態Ｙに切り換えることにより、ポンプポート２２が第１シリンダポート２７に接続され、油圧ポンプ１４によってポンプポート２２に供給された圧油が操作弁２０によって第１操作油路２８に供給されて第１操作油路２８からロッド側油室９ａに供給される。これと共に、第２シリンダポート２９がタンクポート２４に接続され、ボトム側油室９ｂの圧油が第２操作油路３０に排出されて第２操作油路３０から操作弁２０及び排油路２６を介してタンク２５に排油される。これにより、ダンプシリンダ９が油圧ポンプ１４からの圧油によって短縮側に駆動される。すなわち、荷台７が下降操作される。 By switching the operation valve 20 to the lowering operation state Y, the pump port 22 is connected to the first cylinder port 27, and the pressure oil supplied to the pump port 22 by the hydraulic pump 14 is changed by the operation valve 20 to the first operation oil passage 28. Is supplied to the rod-side oil chamber 9a from the first operation oil passage 28. At the same time, the second cylinder port 29 is connected to the tank port 24, the pressure oil in the bottom side oil chamber 9b is discharged to the second operation oil passage 30, and the operation valve 20 and the oil discharge passage 26 are discharged from the second operation oil passage 30. Oil is drained to the tank 25 via the. As a result, the dump cylinder 9 is driven to the shortening side by the pressure oil from the hydraulic pump 14. That is, the loading platform 7 is lowered.

操作弁２０を上昇操作状態Ｘ及び下降操作状態Ｙに切り換えた場合、第１バイパスポート３１及び第２バイパスポート３２のそれぞれがブロックされ、油圧ポンプ１４によるパワーステアリング装置１０への圧油の供給が不可能になってパワーステアリング装置１０が作動しない。 When the operation valve 20 is switched between the up operation state X and the down operation state Y, each of the first bypass port 31 and the second bypass port 32 is blocked, and the hydraulic oil is supplied from the hydraulic pump 14 to the power steering device 10. It becomes impossible and the power steering device 10 does not operate.

操作弁２０を中立状態Ｎに切り換えることにより、図３に示されるように、第１バイパスポート３１とバイパス流路３５とが接続され、かつ、バイパス流路３５と第１シリンダポート２７とがオリフィス付き給油路３６によって接続され、油圧ポンプ１４によって第１バイパスポート３１に供給された圧油がバイパス流路３５及びオリフィス付き給油路３６によって第１操作油路２８に供給されて第１操作油路２８からロッド側油室９ａに供給される。しかし、第２シリンダポート２９がブロックされていてボトム側油室９ｂの圧油の排出が不可能になり、ダンプシリンダ９が駆動されない。すなわち、荷台７が停止される。 By switching the operation valve 20 to the neutral state N, as shown in FIG. 3, the first bypass port 31 and the bypass flow passage 35 are connected, and the bypass flow passage 35 and the first cylinder port 27 are orifices. The hydraulic oil which is connected to the first bypass port 31 by the hydraulic pump 14 is supplied to the first operating oil passage 28 by the bypass passage 35 and the orifice-containing oil passage 36, and the first operating oil passage 28 is connected. It is supplied from 28 to the rod side oil chamber 9a. However, since the second cylinder port 29 is blocked and the pressure oil in the bottom side oil chamber 9b cannot be discharged, the dump cylinder 9 is not driven. That is, the loading platform 7 is stopped.

操作弁２０を中立状態Ｎに切り換えることにより、図３に示されるように、第１バイパスポート３１と第２バイパスポート３２とがバイパス流路３５によって接続され、油圧ポンプ１４によって第１バイパスポート３１に供給された圧油がバイパス流路３５によってパワステ用給油路３４に供給されてパワステ用給油路３４からパワーステアリング装置１０に供給される。すなわち、油圧ポンプ１４によってパワーステアリング装置１０に圧油が供給されてパワーステアリング装置１０の作動が可能になり、パワーステアリング装置１０による前車輪１の操向操作が可能になる。前車輪１を操向操作するパワーステアリング装置１０にサージ圧が発生した場合、サージ圧が操作弁２０に及ぶことによって操作弁２０の内部で圧油がリークし、リークした圧油が第１シリンダポート２７から第１操作油路２８を介してロッド側油室９ａに、第２シリンダポート２９から第２操作油路３０を介してボトム側油室９ｂにそれぞれ流入し、ロッド側油室９ａ及びボトム側油室９ｂのそれぞれにおいて、ダンプシリンダ９のピストン９ｃをスライドさせる操作力が発生する。そして、ボトム側油室９ｂで発生する操作力がロッド側油室９ａで発生する操作力よりも強くなる。油圧ポンプ１４によって第１バイパスポート３１に供給された圧油がバイパス流路３５からオリフィス付き給油路３６に流入し、オリフィス付き給油路３６によって減圧されて第１操作油路２８に供給されて第１操作油路２８からロッド側油室９ａに供給され、ロッド側油室９ａにおいて、オリフィス付き給油路３６によって供給された圧油によってピストン９ｃをスライドさせる操作力が発生する。ボトム側油室９ｂでリーク油圧によって発生したスライド操作力と、ロッド側油室９ａでリーク油圧によって発生したスライド操作力との差がロッド側油室９ａでオリフィス付き給油路３６からの圧油によって発生したスライド操作力によってキャンセルされる。すなわち、パワーステアリング装置１０にサージ圧が発生しても、サージ圧に起因する操作弁２０のリーク圧油によるダンプシリンダ９の伸長作動がオリフィス付き給油路３６による圧油の供給によって防止される。 By switching the operation valve 20 to the neutral state N, as shown in FIG. 3, the first bypass port 31 and the second bypass port 32 are connected by the bypass flow passage 35, and the hydraulic pump 14 allows the first bypass port 31 to be connected. The pressure oil supplied to the power steering device 10 is supplied to the power steering oil supply passage 34 by the bypass flow passage 35 and then supplied to the power steering device 10 from the power steering oil supply passage 34. That is, the hydraulic oil is supplied to the power steering device 10 by the hydraulic pump 14 to enable the operation of the power steering device 10, and the steering operation of the front wheels 1 by the power steering device 10 becomes possible. When a surge pressure is generated in the power steering device 10 that steers and operates the front wheels 1, the surge pressure reaches the operation valve 20, whereby the pressure oil leaks inside the operation valve 20, and the leaked pressure oil is the first cylinder. The oil flows from the port 27 into the rod-side oil chamber 9a via the first operation oil passage 28, and from the second cylinder port 29 into the bottom-side oil chamber 9b via the second operation oil passage 30, respectively. An operation force for sliding the piston 9c of the dump cylinder 9 is generated in each of the bottom side oil chambers 9b. Then, the operating force generated in the bottom side oil chamber 9b becomes stronger than the operating force generated in the rod side oil chamber 9a. The pressure oil supplied to the first bypass port 31 by the hydraulic pump 14 flows into the oil supply passage 36 with an orifice from the bypass flow passage 35, is reduced in pressure by the oil supply passage 36 with an orifice, and is supplied to the first operation oil passage 28. The operation oil is supplied from the first operation oil passage 28 to the rod-side oil chamber 9a, and in the rod-side oil chamber 9a, the operation oil for sliding the piston 9c is generated by the pressure oil supplied by the oil supply passage 36 with the orifice. The difference between the slide operating force generated by the leak hydraulic pressure in the bottom side oil chamber 9b and the slide operating force generated by the leak hydraulic pressure in the rod side oil chamber 9a is caused by the pressure oil from the oil supply passage 36 with the orifice in the rod side oil chamber 9a. It is canceled by the generated slide operation force. That is, even if a surge pressure is generated in the power steering device 10, the extension operation of the dump cylinder 9 due to the leak pressure oil of the operation valve 20 due to the surge pressure is prevented by the supply of the pressure oil by the oil supply passage 36 with the orifice.

〔ロプスの構成について〕
ロプス６は、図１に示されるように、運転部５の左横側部及び右横側部のそれぞれに設けられたサイドロプス部材６ａと、左右のサイドロプス部材６ａの前上部どうしを連結する前連結ロプス部材６ｂと、左右のサイドロプス部材６ａの後上部どうしを連結する後連結ロプス部材６ｃと、を有している。 [About the structure of ROPS]
As shown in FIG. 1, the lops 6 connect the side lops members 6a provided on each of the left lateral side and the right lateral side of the driving section 5 to the front upper portions of the left and right side lops members 6a. It has a front connecting lops member 6b and a rear connecting lops member 6c for connecting the rear upper portions of the left and right side lops members 6a.

左右のサイドロプス部材６ａのそれぞれに対する前連結ロプス部材６ｂの連結は、図４に示されるように、サイドロプス部材６ａに取付けられたブラケット４０と、前連結ロプス部材６ｂの端部に備えられたフランジ部４１とが連結ボルト４２及びナット４３によって締め付け連結されることによって行われる。ブラケット４０は、サイドロプス部材６ａに溶接によって取り付けられている。ブラケット４０に補強プレート４４が溶接によって付着されている。ナット４３は、補強プレート４４に溶接によって取り付けられている。連結ボルト４２は、ブラケット４０及び補強プレート４４に対してフランジ部４１が位置する側から挿通させてナット４３に締め込むようになっている。 Connection of the front connecting lops member 6b to each of the left and right side lops members 6a is provided on the bracket 40 attached to the side lops member 6a and an end portion of the front connecting lops member 6b, as shown in FIG. It is performed by tightening and connecting the flange portion 41 with the connecting bolt 42 and the nut 43. The bracket 40 is attached to the side lobe member 6a by welding. A reinforcing plate 44 is attached to the bracket 40 by welding. The nut 43 is attached to the reinforcing plate 44 by welding. The connecting bolt 42 is inserted into the bracket 40 and the reinforcing plate 44 from the side where the flange portion 41 is located, and is fastened to the nut 43.

〔別実施形態〕
（１）上記した実施形態では、荷台７を前側部分が上下揺動する状態で備えている例を示したが、横側部分が上下揺動する荷台を備えるものであってもよい。 [Another embodiment]
(1) In the above-described embodiment, an example in which the luggage carrier 7 is provided in a state in which the front side portion vertically swings has been described, but the lateral side portion may include a luggage carrier that vertically swings.

（２）上記した実施形態では、パワーステアリング装置１０が全油圧式である例を示した、リンケージ式のものであってもよい。 (2) In the above-described embodiment, the power steering device 10 may be of linkage type, which is an example of full hydraulic type.

（３）上記した実施形態では、オリフィス付き給油路３６が操作弁２０に形成されている例を示したが、操作弁２０の外部に設けたものであってもよい。 (3) In the above-described embodiment, an example in which the oil supply passage 36 with an orifice is formed in the operation valve 20 is shown, but it may be provided outside the operation valve 20.

（４）上記した実施形態では、前車輪１が操向操作される走行車輪である例を示したが、後車輪が操向操作されるものであってもよい。 (4) In the above-described embodiment, the example in which the front wheels 1 are traveling wheels that are steered is shown, but the rear wheels may be steered.

本発明は、多目的作業車に限らず、農作物の収穫作業など各種の作業を行う荷台付きの作業車に適用できる。 INDUSTRIAL APPLICABILITY The present invention is not limited to a multipurpose work vehicle, but can be applied to a work vehicle with a bed for performing various operations such as harvesting of agricultural products.

１ 走行車輪（前車輪）
７ 荷台
９ ダンプシリンダ
９ａ ロッド側油室
１０ パワーステアリング装置
１４ 油圧ポンプ
２０ 操作弁
２７ シリンダポート（第１シリンダポート）
３５ バイパス油路
３６ オリフィス付き給油路 1 traveling wheel (front wheel)
7 Loading Platform 9 Dump Cylinder 9a Rod Side Oil Chamber 10 Power Steering Device 14 Hydraulic Pump 20 Operation Valve 27 Cylinder Port (First Cylinder Port)
35 bypass oil passage 36 oil supply passage with orifice

Claims (2)

走行車輪を操向操作する油圧式のパワーステアリング装置と、
上下揺動可能な荷台と、
前記荷台に連動連結され、伸長作動によって前記荷台を上昇揺動操作し、短縮作動によって前記荷台を下降揺動操作する油圧式かつ複動形のダンプシリンダと、
前記ダンプシリンダの操作弁に圧油を供給する油圧ポンプと、
前記操作弁に形成され、前記操作弁の中立状態で前記油圧ポンプからの圧油を前記パワーステアリング装置に供給するバイパス流路と、
前記操作弁の中立状態において、前記油圧ポンプからの圧油を前記ダンプシリンダのロッド側油室に供給するオリフィス付き給油路と、が備えられた作業車。 A hydraulic power steering device that steers the traveling wheels,
With a platform that can swing up and down,
A hydraulic and double-acting dump cylinder, which is coupled to the cargo bed, performs an upward rocking operation on the cargo bed by an extension operation, and lowers an rocking operation on the cargo bed by a shortening operation,
A hydraulic pump for supplying pressure oil to the operation valve of the dump cylinder;
A bypass flow path which is formed in the operation valve and which supplies the pressure oil from the hydraulic pump to the power steering device in a neutral state of the operation valve;
An oil supply passage with an orifice that supplies pressure oil from the hydraulic pump to a rod-side oil chamber of the dump cylinder in a neutral state of the operation valve. 前記オリフィス付き給油路は、前記操作弁の中立状態で前記バイパス流路と、前記操作弁のシリンダポートと、を接続する状態で前記操作弁に形成されている請求項１に記載の作業車。 The work vehicle according to claim 1, wherein the oil supply passage with the orifice is formed in the operation valve in a state where the bypass passage and the cylinder port of the operation valve are connected in a neutral state of the operation valve.
JP2019018982A 2019-02-05 2019-02-05 work vehicle Active JP7106466B2 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP2019018982A JP7106466B2 (en) 2019-02-05 2019-02-05 work vehicle
US16/693,773 US11161543B2 (en) 2019-02-05 2019-11-25 Work vehicle having a hydraulic circuit
EP19212318.0A EP3693215B1 (en) 2019-02-05 2019-11-28 Work vehicle

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JP2004283189A (en) * 2003-03-19 2004-10-14 Daifuku Co Ltd Vehicle installation type lift device for nursing
US20140318116A1 (en) * 2011-12-08 2014-10-30 Kawasak Jukogyo Kabushiki Kaisha Hydraulic control device and construction machinery including same

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SE527434C8 (en) * 2004-07-28 2006-03-28 Volvo Constr Equip Holding Se Hydraulic system and work machine including such a system
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Publication number Priority date Publication date Assignee Title
JPS5893633A (en) * 1981-11-30 1983-06-03 Kubota Ltd Dumping type truck
JPH02258437A (en) * 1989-03-31 1990-10-19 Kayaba Ind Co Ltd Hydraulic control device for dump
JP2004283189A (en) * 2003-03-19 2004-10-14 Daifuku Co Ltd Vehicle installation type lift device for nursing
US20140318116A1 (en) * 2011-12-08 2014-10-30 Kawasak Jukogyo Kabushiki Kaisha Hydraulic control device and construction machinery including same

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US20200247467A1 (en) 2020-08-06
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US11161543B2 (en) 2021-11-02
EP3693215A1 (en) 2020-08-12

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